The Northern Yellowstone Cooperative Wildlife Working Group conducted its annual, late-winter, classification of northern Yellowstone elk on March 24th. Biologists used a helicopter to classify a total of 4,200 elk as bulls, cows, or calves in specified sampling areas through the entire northern winter range during the 1-day survey. Northern Yellowstone elk winter between the northeast entrance of Yellowstone National Park and Dome Mountain/Dailey Lake in the Paradise Valley.

Estimated sex and age ratios for the population were 12 calves, 4 yearling bulls (i.e. spikes), and 18 adult (i.e., branch-antlered) bulls per 100 cows. The estimated ratio of 12 calves per 100 cows is similar to the late-winter ratio of 14 calves per 100 cows during 2002, but less than the range of 22 to 34 calves per 100 cows observed during the previous six years. The causes of this year's low recruitment are most likely predation and drought-related effects on maternal condition and calf survival.

The Working Group will continue to monitor trends of the elk population and evaluate the relative contribution of various components of mortality, including predation, environmental factors, and hunting. The Working Group was formed in 1983 to cooperatively preserve and protect the long-term integrity of the northern Yellowstone winter range for wildlife species by increasing our scientific knowledge of the species and their habitats, promoting prudent land management activities, and encouraging an interagency approach to answering questions and solving problems. The Working Group is comprised of resource managers and biologists from the Montana Fish, Wildlife, & Parks; National Park Service (Yellowstone National Park); U.S. Forest Service (Gallatin National Forest); and U.S. Geological Survey-Northern Rocky Mountain Science Center, Bozeman.

Information provided by the NPS

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